BRYOZOA. 271 
Dekayella prenuntia.] 
vary considerably both in number and size, with medium conditions about as in 
fig. 43. Acanthopores comparatively small, the principal set comparing in number 
with the zocecia about as one is to four ; small set very minute, not often preserved, 
at any rate, only rarely distinguishable in sections. 
Mus. Reg. Nos. 6019, 6020, 8073, 8305. 
Var. SIMPLEX, 7. var. 
PLATE XXIII, FIGS, 39-42. 
In this form the mesopores are reduced numerically to a minimum. Indeed, 
they are not distinguishable externally, and only a very few are to be made out in 
tangential sections. The zocecial apertures are polygonal and unusually regular in 
their arrangement. The walls, too, get to be stronger than in any other form of the 
genus, with perhaps one exception, while the acanthopores are, if not smaller, at any 
rate less noticeable in thin sections. From an external examination merely speci- 
mens of this species might be regarded, and with good reason, as belonging to the 
Amplexoporide. Certainly they would scarcely be suspected of being closely related 
to Dekayella prenuntia. But with the aid of thin sections, vertical ones especially, 
the true affinities of the form become obvious at once. Excepting that mesopores 
are practically wanting, there is little or no difference between vertical sections of 
the typical form of the species and var. simplex. 
Mus. Reg. No. 8307. 
Var. NEVIGERA, 7”. var. 
(Not Figured.) 
This form differs from the preceding in having thinner zocecial walls, and clus- 
ters of from five to thirty mesopores at the center of the usual groups of large 
zocecia. In the var. simpler the zoarium consists generally of but few branches, but 
in the best examples of the present form they are numerous, strong and divide and 
inosculate freely, the whole forming a mass over 70 mm. in diameter. 
Mus. Reg. Nos. 6018, 7669. 
Var. ECHINATA, 7. var. 
PLATE XXIII. FIGS. 32-38. 
This variety grows in large compressed branches, that seem never to inosculate. 
The clusters of large cells are moderately distinct, and frequently enclose small 
aggregations of mesopores. In having very few mesopores their structure agrees 
